Republican leaders returned to Washington after a lengthy Easter recess with two discrete goals for the week: Keep the federal government from shutting down, and maybe, if they had the time and the votes, finally pass their bill to replace the Affordable Care Act.

Congress being Congress, this presented a test significantly more difficult than, say, walking and chewing gum at the same time. And as a deadline for funding the government draws near, one GOP priority is threatening to derail the other.

House Democrats on Thursday warned that they would withhold their support for a short-term extension of government funding if Republicans first tried to rush through legislation decimating Obamacare, while an impatient President Trump accused them of wanting to shut down the government for not agreeing to his demands. The rhetorical volleys injected a new round of drama into a spending showdown that had seemed close to a resolution. But it wasn’t clear that any of the threats would actually be carried out.

The deadline for Congress to pass some sort of extension of government funding is Friday at midnight. Negotiators have been making progress on legislation that would appropriate money for the remaining five months of the fiscal year, and those talks picked up steam once Trump relented on his demand for border-wall money and agreed to Democratic demands that the administration continue paying out a key Obamacare subsidy for insurers. But with a deal yet to be struck, Republicans introduced a measure to extend current funding for another week, hoping to buy time for negotiations without shuttering national parks and museums or sending thousands of federal employees home for a few days.

Such stopgap bills, known as continuing resolutions, are routine. The government has actually been operating on one for the last seven months. But Democrats have watched with growing alarm as Republicans make another push to pass the health-care bill they abandoned a month ago, and they sensed an opportunity to blunt the GOP’s new momentum. Though Republicans control the majority in both the House and the Senate, they’ve had to repeatedly rely on Democratic votes to pass even non-controversial spending bills over the opposition of hard-line conservatives. “I’ve bailed them out a number of times,” Nancy Pelosi, the House Democratic leader, reminded reporters on Thursday.

With that in mind, Pelosi told Speaker Paul Ryan her party wouldn’t help him keep the government open if he scheduled a vote on the GOP’s revised American Health Care Act, which party leaders are considering for Friday or Saturday—if they can get the votes. “If Republicans pursue this partisan path of forcing Americans to pay more for less and destabilizing our country’s health-care system—without even knowing how much their bill will cost—Republicans should be prepared to pass a one-week continuing resolution on their own,” Representative Steny Hoyer of Maryland, the second-ranking House Democrat and the party’s chief vote-counter, said in a statement.

If Democrats followed through, they’d be exacting a kind of revenge on Republicans, who shut down the government for 17 days in 2013 in an unsuccessful bid to cut off funding for Obamacare. Now it’s the preservation of the same law for which the Democrats are fighting.

Their threat might be premature, however. Although Ryan won the endorsement of the House Freedom Caucus on Wednesday for the amended health-care bill, GOP leaders were struggling to win the support of moderates who can now determine the measure’s fate and who are irritated that conservatives succeeded in pushing it to the right. About a dozen were publicly against the bill a month ago before it included a provision gutting Obamacare’s protection for people with pre-existing conditions. And the amendment written by Representative Tom MacArthur of New Jersey could be losing more votes than it gains among the GOP’s more politically vulnerable members. One more moderate lawmaker, Representative Patrick Meehan of Pennsylvania, announced his opposition to the new bill on Thursday. Republicans can afford no more than 22 defections to get 216 votes for a majority.

“We’ve not yet made any decisions on a vote,” Ryan told reporters on Thursday morning. He said the House would only take up the health-care bill once Republicans knew it had the votes to pass. And while the speaker argued that the effort was “making very good progress” after the addition of the MacArthur amendment, he gave no indication that a vote was imminent.

With the Obamacare repeal bill suddenly alive, Democrats searched desperately for arguments that would help Republican moderates hold the line. Holding a press conference with reporters and their young children on “Bring Your Kids to Work Day” at the Capitol, Pelosi adopted a scatological approach. “The minute they cast that vote they put doo-doo on their shoe, a tattoo on their forehead,” she said. Senate Minority Leader Charles Schumer warned Republican moderates their seats were at risk if they voted for a bill that took health care away from their constituents and which fewer than one in five Americans supported, according to a March poll by Quinnipiac University. “We hope that Republicans don’t pass it,” Schumer said. “But if it does, American politics will take its effect.”

As to a government shutdown, Schumer backed the House Democrats’ threat, but suggested a broader deal on spending was close at hand. “There are some sticking points that remain, but I’m optimistic we can come up with an agreement very soon,” he said.

While the negotiations took place on Capitol Hill, the president attacked Democrats in a series of tweets that brought more confusion than clarity to the dispute. He suggested they were willing to shut down the government if the administration didn’t “give billions to their insurance companies,” although that sticking point appeared to have been resolved on Wednesday—when Trump’s chief of staff, Reince Priebus, informed Democratic leaders that payments to insurance companies would continue. And Trump blamed Democrats for blocking health benefits for coal miners, although it is a Democratic senator, Joe Manchin of West Virginia, who has been pushing against GOP resistance for that provision to be funded. “Joe Manchin must have fallen out of bed” when he read that, Schumer quipped. “It was out of touch with reality, that tweet,” he said. His spokesman, Matt House, went further, suggesting on Twitter that Trump was displaying “a startling lack of awareness of where the negotiations actually are.”

It’s conceivable that Trump was lashing out after hearing of the Democrats’ threat to block a funding bill if Republicans voted on the health-care bill, which the White House has been pushing aggressively. They know the president desperately wants a show of progress for his 100th day in office on Saturday, and they are equally motivated to thwart him—even if it means causing a shutdown over a health-care bill that remains a long way from becoming law.